The Grassks of Tennessee. Iu9 



7. Spikelets heterogamous;in pairs, one sessile, herma])hro(lite; 

 one pedicellate, staminate or neuter . . . . 6. Andropogon. 



7. Spikelets all alike 8 



8. Spikelets awnless ... 4. Saccharum. 



8. Spikelets awned 9 



9. Racemes forming a broad, fan-shaped panicle . .3. Miscanthus. 

 9. Racemes upon an elongated main axis forming a much 



branched panicle, branches articulated 5. Erianthus. 



TO. (ilumes (including the flowering) three 7. Paspalum. 



10. Glumes four, the lowest usually smaller than the others 



(wanting in Panicum filiforrne) 11 



11. Spikelets surrounded by an involucre consisting of one to 



many bristles, which are sometimes grown together be- 

 coming bur-like 12 



11. Spikelets not surrounded by bristles or special covering.. 



8. Panicum. 



12. Bristles persistent (See Fig. 41.) 9. Setaria. 



1 2. Bristles falling with the spikelets 13 



13. Bristles grown together at the base, forming a bur-like cover- 



ing over the spikelets 10. Cenchrus. 



13. Bristles distinct 11. Pennisetum. 



14. Spikelets unisexual, monoecious, ovate or elliptical, the pistil- 



late above and the staminate below in the same inflor- 

 escence 12. Zizaniopsis. 



14. Spikelets all hermaphrodite 15 



15. Empty glumes two, small. (See Fig. 43.) 13. Oryza. 



15. Empty glumes none . . 14. Leersia. 



16. Culms perennial, woody, leaf-blade articulated with the 



sheath (Tribe Bambuse.e.) 64. Arundinaria. 



16. Culms annual, herbaceous, leaf-blade continuous with the 



sheath 17 



17. Spikelets distinctly pedicellate, in racemes or panicles (these 



sometimes spike-like) iS 



17. Spikelets sessile, in true spikes, (sometimes on very short 



pedicels and then in one-sided or unilateral racemes) 36 



1 8. Spikelets one-flowered 19 



1 8. Spikelets two to many-flowered 30 



19. Empty glumes four, the third and fourth very unlike the 



first and second and falling with the fruiting glume 

 (Tribe Phalaride.e.) 20 



19. Empty glumes two 21 



20. Third and fourth glumes reduced to narrow scales or bristles, 



awnless 15. Phalaris. 



20. Third and fourth glumes smaller than the first and second, 

 awned. (See Fig. 45.) 16. Anthoxanthum. 



